Turnstone container-VM: podman image -> boco qcow2 boot

Arch image with turnstone (venv), dev toolkit, rootless podman; boots
via boco (virtiofs shares, direct UID mapping for nested virtiofs).
sshd ops channel + turnstone-server as guest marvin; state (SQLite db,
config, work) on host shares; LLM via the TensorX OpenAI-compatible
gateway (https://api.tensorx.ai/v1), reachable from the guest through
both slirp layers with no relay.

.gitignore

@@ -0,0 +1,12 @@
+# VM state (SQLite db) — created at runtime
+data/*
+!data/.gitkeep
+
+# Agent workspace
+work/*
+!work/.gitkeep
+
+# Secrets: private ssh key + derived pubkey, real turnstone config
+configs/ssh/id_ed25519*
+configs/ssh/authorized_keys
+configs/turnstone/config.toml